Subsurface wave power generation systems and methods

ABSTRACT

A subsurface wave power generation system includes a seabed mounting plate adapted for securing to a seabed, a wing having generally opposed first and second wing surfaces extending between a first and second wing ends, the second wing end being pivotably mounted to the seabed mounting plate such that pivoting motion about a pivot axis generally parallel to the mounting plate is imparted to the wing by subsurface wave action acting on the first and second wing surfaces, and a drive arm pivotably connected to the wing to convert the pivoting motion into reciprocal motion. An electrical generator can be driven by the drive arm through a slip linkage. The slip linkage includes a first stage that converts the reciprocal motion of the drive arm into rotational motion and a second stage that selectively engages the a drive shaft of the generator drive to impart the rotational motion thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/543,133, filed on Aug. 18, 2009, which claims the benefit of U.S.Provisional Application Ser. No. 61/189,309, filed on Aug. 18, 2008, thecontent of which applications are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates to the generation of power by harnessinghydro-kinetic energy, and more particularly, to the generation ofelectrical power from subsurface wave action.

BACKGROUND OF THE INVENTION

With the potential downsides of conventional fossil fuel and nuclearpower sources well known, ongoing efforts are being made to practicallyand economically exploit clean, renewable power sources. The energylatent in the movement of water, or hydro-kinetic energy, was one ofhumankind's earliest power sources and is increasingly being looked toagain for clean, renewable power.

Where there is a consistent and rapid flow of water, generatinghydro-kinetic power is relatively easy. For example, many hydroelectricplants have been established in connection with dams along rivers.Unfortunately, the environmental impact of damming a river can be quitehigh. Limited efforts have been made to place turbines directly onriverbeds, to allow river power to be harnessed without the majorenvironmental impact of a dam. However, such turbine systems stillrequire the presence of a suitable river.

Harnessing tidal energy is another approach being explored, and to somedegree, exploited. While tidal energy is theoretically available alongall ocean coastlines, tidal flow characteristics vary greatly from placeto place. Additionally, the approximately 12 hour tidal cycle does notlend itself to continuous power generation at a given location. Instead,recurring periods of virtually no tidal flow will alternate with longperiods of increasing and decreasing flow.

Although wave magnitude can vary greatly between coastal locations, someappreciable wave action is likely to be present along virtually allocean coastlines. Additionally, larger lakes and seas can experiencesignificant wave action. However, most wave power systems being testedtend to focus on surface waves. While wave magnitude is generallygreatest at the surface, it is also more prone to significantfluctuations with changes in wind conditions. These fluctuations canmore readily result in damage to, or loss of, power generatingequipment. Also, at least some components of the power generatingequipment must be at or very near the surface, where such components canpresent a hazard to navigation.

Subsurface wave action at relatively shallow depths underwater(approximately 30-80 feet), while correlating to surface wave activity,tends to be much more regular. Accordingly, subsurface wave actionrepresents a potentially widespread and consistently-utilizable sourceof clean, renewable power. Attempts have been made to utilize subsurfacewave action for power generation, including the development of systemswith pivotably mounted wings that move back and forth with the waveaction; however, further improvements are possible.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide improved systems and methods for subsurface wave powergeneration. According to an embodiment of the present invention, asubsurface wave power generation system includes a seabed mounting plateadapted for securing to a seabed, a wing having generally opposed firstand second wing surfaces extending between a first wing end and a secondwing end, the second wing end being pivotably mounted to the seabedmounting plate such that pivoting motion about a pivot axis generallyparallel to the mounting plate is imparted to the wing by subsurfacewave action acting on the first and second wing surfaces, and a drivearm pivotably connected to the wing to convert the pivoting motion intoreciprocal motion.

According to an aspect of the present invention, a wing directionalplate is rotatably mounted to the seabed mounting plate. The wing ispivotably connected to the seabed mounting plate via the rotatingdirection plate, such that the wing is rotatable about a rotation axisgenerally perpendicular to the seabed mounting plate.

According to another aspect of the present invention, the wing includesa float arranged along the first wing end and urging the wing into avertical position. According to an additional aspect of the presentinvention, the first and second wing surfaces are both concave.

According to a further aspects of the present invention, the systemincludes an electrical generator driven by the drive arm. The drive armdrives the electrical generator through a slip linkage. The slip linkageincludes a first stage that converts the reciprocal motion of the drivearm into rotational motion and a second stage that selectively engagesthe a drive shaft of the generator drive to impart the rotational motionthereto.

According to a method aspect of the present invention, A method forharnessing subsurface wave power includes displaceably mounting agenerally trapezoidal, biconcave wing underwater oriented generallyperpendicularly to a sub-surface wave propagation direction, andreciprocating a drive arm using generally cyclic displacement of thewing.

These and other objects, aspects and advantages of the present inventionwill be better appreciated in view of the drawings and followingdetailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top view of a subsurface wave power generationsystem including a pivotally mounted wing and an electrical generatorassembly, according to an embodiment of the present invention;

FIG. 2 is a schematic side view of the subsurface wave power generationsystem of FIG. 1;

FIG. 3 is a schematic front view of the wing of FIG. 1, with hiddencomponents shown in broken lines;

FIG. 4 is a schematic side view of the wing of FIG. 1, with hiddencomponents shown in broken lines and partially cutaway to show details;

FIG. 5 is a schematic side view of an alternate embodiment of the wingof FIG. 1, with hidden components shown in broken lines;

FIG. 6 is a schematic side view of another embodiment of the wing ofFIG. 1, with hidden components shown in broken lines;

FIG. 7 is a schematic plan view of the electrical generator assembly ofFIG. 1, including a slip linkage;

FIG. 8 is schematic sectional view of the slip linkage of FIG. 7;

FIG. 9 is a section view taken along line 9-9 of FIG. 8;

FIG. 10 is the sectional view of FIG. 9, in an alternate position; and

FIG. 11 is a partial schematic view of another embodiment of theelectrical generator assembly of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, according to an embodiment of the presentinvention, a subsurface wave power generation system 10 includes a wingassembly 12 and an electrical generator assembly 14 connected by a drivearm 16. The wing assembly 12 includes a wing 20 that is pivotablymounted to the seabed 22, such that subsurface wave action imparts apivoting motion 24 to the wing 20. The drive arm 16 connects to the wing20 and converts the pivoting motion into a reciprocal motion 26 forutilization by the electrical generator assembly 14. The electricalgenerator assembly 14 is adapted to transmit generated electricity toshore and to send and receive data and command/control information fromoff-site.

Although the present embodiment is described in connection with anelectrical generator assembly 14 drive by the wing assembly 12, it willappreciated that the wing assembly 14 could be used to drive otherloads. For example, the wing assembly 14 could drive water purificationsystem, such as a reverse osmosis system. Additionally, it will beappreciated that the system 10 could include an array wing assemblies 12and related components in a given location.

The wing assembly 12 further includes a seabed mounting plate 30securely seated upon the seabed 22. A wing directional plate 34 isrotatably mounted to the seabed mounting plate 32, and a wing mountingrail 36 is arranged on the directional plate 34. A carriage mechanism 38allows the wing 20 to travel in a sliding motion 42 and the pivotingmotion 24 relative to mounting rail 36. As a result, the wing 20 is ableto move in the pivoting motion 24, the sliding motion 42 and a rotatingmotion 44 in response to subsurface wave action. It will be appreciatedthat the directional plate 34 and/or the rail 36 could be omitted, suchthat the wing 20 was simply pivotably mounted directly to the mountingplate 30. Additionally, it will be appreciated that a wing that was onlyslidably displaceable upon the mounting plate 30 could be used.

Preferably, the wing 20 is able to travel approximately 180 degrees,(+/− approximately 90 degrees from an upright position) in the pivotingdirection 24 under the influence of subsurface wave action. Adirectional vane 46 extends from the wing directional plate 34 to helpkeep the wing 20 approximately broadside on to the prevailing directionof subsurface waves. Stopping blocks 50 limit the sliding and rotatingmotions 42, 44 of the wing 20. Preferably, the rotating motion 44 islimited to approximately 14 degrees to avoid excessive stresses on thedrive arm 16.

The drive arm 16 traverses a plurality of universal joints 52 tofacilitate the transition between the pivoting motion 24 of the wing 20and the reciprocal motion 26 to be supplied to the electrical generatorassembly 14. Additionally, the joints 52 can accommodate some rotationof the wing 20 on the wing directional plate 36. Preferably, the drivearm 16 attaches at or near the center of the wing 20, although multiplealternate attachment points could be included. It will appreciated thatthe drive arm 16 could include further joints to traverse additionalangles, as well as to branch into multiple drive arms to supply multiplegenerator assemblies 14 or other loads. If desired, a second drive arm16 (see broken lines) could be added opposing the first drive arm, andone or more additional loads connected thereto.

Referring to FIGS. 3 and 4, the wing 20 has generally opposed first andsecond wing surfaces 60, 62 extending between first and second wing ends64, 66. A float 70 extends along the first wing end with sufficientbuoyancy to urge the wing 20 upright following pivoting movement awayfrom vertical. The second wing end 66 connects to the carriage mechanism38 (including pivot joints 72 allowing pivoting motion between thesecond wing end 66 and a sliding carriage 74). Generally wedge-shapedside panels 76 extend between the first and second wing surfaces 60, 62.

The first and second wing surfaces 60, 62 are both concave, resulting ina biconcave arrangement that is believed to enhance the pressure exertedon the wing 20 through a pivoting cycle, together with the side panels76 and the float 70. Internal framework 80 adds strength and rigidity tothe wing. The framework 80 is reinforced near the center of the wing 20,to allow for more secure attachment of the driving arm 16.

Referring to FIGS. 5 and 6, wings can be equipped with rough weathersurvival features to prevent or minimize damage during periods ofdangerously high subsurface wave action. Referring particularly to FIG.5, the first and second wing surfaces 60′, 62′ of a wing 20′ incorporatea plurality of louvers 86′. The louvers 86′ open to allow water to passthrough the wing 20′, decreasing the thrust exerted thereon. A louvercontrol motor 88′, or other device, can be used to selectively open andclose the louvers 86′, or the louvers can simply be biased to remainclosed until a predetermined thrust level is reached.

Where the louvers 86′ are selectively opened and closed, advantageously,operation is automatic based upon weather conditions. For instance, thesystem 10 can receive weather forecast data and open and closed thelouvers 86′ based thereon. Alternately, the system 10 can sense localweather conditions. In the latter example, the system 10 can also beused to provide weather data to interested parties.

Referring to FIG. 6, the wing 20″ can be folded down flat to ride outrough weather. To facilitate lay down of the wing 20″, the drive arm 16″can include a solenoid-activated telescoping extension 90″. Anelectromagnetic 92″ could also be arranged in the mounting plate 30″ tofacilitate lay down, as well as a normally slack cable drive 94″ thatcould spool in to securely lay down the wing 20″. It will be appreciatedthat the various features of FIGS. 5 and 6 could be used separately orin various combinations.

Referring to FIG. 7, the electrical generator assembly 14 includes arotating electrical generator 100, a generator drive shaft 102, a sliplinkage 104 and control/power electronics 106 arranged within awatertight housing 110. The generator 100 and drive shaft 102 preferablyrotates unidirectionally rotation direction 112. The slip linkage 104converts the reciprocal motion 26 of the drive arm 16 into theunidirectional rotation in direction 112. Electricity generated by thegenerator 100 is transmitted back to shore (or to other electricalload(s)), and data and command can be sent and received by thecontrol/power electronics 106.

It will be appreciated that any suitable generator 100 could be used,including AC and/or DC generators, and self-excited orseparately-excited generators. Where a separately-excited generator isused, or for a generator requiring field flashing, field generationequipment can also be run off of the drive shaft 102. Advantageously,the slip linkage 104 of the present invention allows conventionalrotating generator equipment to be used, although custom-builtgenerators could also be employed in connection with the system 10.

Preferably, the drive arm 16 enters the housing 110 through suitablestuffing boxes, seals or the like to prevent excess water intrusion. Awater pump (not shown) may be included to periodically remove water fromthe housing 110. A joint 56 can be located inside the housing 110, whichcan facilitate disconnection of the drive arm 16 for maintenance andhelp ensure even level reciprocal motion of the drive arm 16 relative tothe slip linkage 104. Suitable combinations of bearings, such as thrustbearings, journal bearings, ring bearings and air bearings, can be usedto help ensure proper alignment and low friction rotation of generatorassembly 14 components.

Referring to FIG. 8, the slip linkage 104 includes a threaded terminalend 120 of the drive arm 16, a threaded collar 122, a rotationtransmission sleeve 124 and a terminal end 126 of the generator driveshaft 102. The slip linkage 104 effectively has a first stage 132 thatconverts the reciprocal motion 26 of the drive arm into unidirectionalrotational motion 112, and a second stage 134 that selectively engagesthe generator drive shaft 102 to impart the rotational motion thereto112.

The threading on the terminal end 120 of the drive arm 16 and on theinterior of the threaded collar 122 can be of any suitable design thatpermits the collar 122 to rotate as a result of reciprocation of thedrive arm 16 while retaining a limited freedom of reciprocal motion. Thecollar 122 will rotate in direction 112 when the drive arm 16 moves inone direction and will rotate counter to the direction 112, when thedrive arm 16 moves in the opposite direction.

When rotating in the direction 112, the threaded collar 122 will beurged toward the sleeve 124 and teeth 140 extending from the threadedcollar 122 will engage corresponding recesses 142 in the sleeve 124(FIG. 9). When rotating counter to the direction 112, the teeth 140 willbe disengaged from the recesses 142 and the sleeve 124 will continue torotate in the direction 112 (FIG. 10). A flywheel 146 or the like can beconnected with the sleeve 124 to help conserve angular momentum when notbeing engaged by the collar 122.

A freewheel mechanism 150 extends between the rotation transmissionsleeve 124 and the terminal end 126 of the generator drive shaft 102.When the rotational velocity of the of the drive shaft 102 is less thanor equal to that of the sleeve 124, the mechanism 150 will engage untilthe drive shaft 102 speed again exceeds that of the sleeve 124. As aresult, the risk of reverse motoring the drive arm 16 from the generatoris reduced. The freewheel mechanism 150 can be a simple centrifugalarrangement, although other, more complex and controllable arrangementscan be used. Additionally, generator drive shaft over speed protectioncan be implemented to disengage the drive shaft 102 if the rotationalspeed of the sleeve 124 becomes too high for the generator. Also,various reduction and/or amplification gearing arrangements can be used.

Referring to FIG. 11, in an alternate embodiment, a generator assembly14′ includes fluid chamber 160′ in which a piston 162′ on the end of adrive shaft 16′ reciprocates, forcing fluid into and out of the chamber160′ past a turbine 164. The turbine 164′ rotates, turning a generator100′, which in turn generates electricity. The turbine 164′ ispreferably selected from among those types which rotateunidirectionally, regardless of the direction of fluid flow past theirvanes.

In general, the foregoing description is provided for exemplary andillustrative purposes; the present invention is not necessarily limitedthereto. Rather, those skilled in the art will appreciate thatadditional modifications, as well as adaptations for particularcircumstances, will fall within the scope of the invention as hereinshown and described and the claims appended hereto.

1. A subsurface wave power generation system comprising: a seabedmounting plate adapted for securing to a seabed; a wing having generallyopposed first and second wing surfaces extending between a first wingend and a second wing end, the second wing end being pivotably mountedto the seabed mounting plate such that pivoting motion about a pivotaxis generally parallel to the mounting plate is imparted to the wing bysubsurface wave action acting on the first and second wing surfaces; anda drive arm pivotably connected to the wing to convert the pivotingmotion into reciprocal motion.
 2. The system of claim 1, wherein thewing is pivoting through a 180 degree arc relative to the seabedmounting plate.
 3. The system of claim 1, further comprising a wingdirectional plate rotatably mounted to the seabed mounting plate, thewing being pivotably connected to the seabed mounting plate via therotating direction plate, such that the wing is rotatable about arotation axis generally perpendicular to the seabed mounting plate. 4.The system of claim 3, wherein the wing directional plate includes adirectional vane extending therefrom, the directional vane beingoriented generally perpendicular to the first and second wing surfaces.5. The system of claim 3, wherein the wing directional plate is limitedto approximately 14 degrees of rotation relative to the seabed mountingplate.
 6. The system of claim 1, further comprising a wing mounting railarranged on the seabed mounting plate, the wing being slidably andpivotably connected to the seabed mounting plate via the wing mountingrail.
 7. The system of claim 1, wherein the wing includes a floatarranged along the first wing end and urging the wing into a verticalposition.
 8. The system of claim 1, wherein the first and second wingsurfaces are both concave.
 9. The system of claim 8, wherein the wingincludes first and second side panels extending arranged at oppositeedges of the first and second wing surfaces.
 10. The system of claim 9,wherein the side panels are generally wedge-shaped.
 11. The system ofclaim 1, wherein the first wing end is thicker than the second wind end,such that the wing has a generally trapezoidal cross section.
 12. Thesystem of claim 1, wherein the wing includes selectively operablelouvers, the louvers permitting water flow through the wing when open.13. The system of claim 12, wherein the louvers are automaticallycontrolled to open and close based upon sea conditions.
 14. The systemof claim 1, wherein the wing is adapted to be selectively locked down tothe seabed mounting plate.
 15. The system of claim 1, wherein the drivearm is approximately centrally connected to the first wing surface. 16.The system of claim 1, further comprising an electrical generator drivenby the drive arm.
 17. The system of claim 1, further comprising a sliplinkage through which the drive arm drives the electrical generator. 18.The system of claim 17, wherein the electrical generator includes arotating generator drive shaft and the slip linkage includes a firststage that converts the reciprocal motion of the drive arm intounidirectional rotational motion and a second stage that selectivelyengages the generator drive shaft to impart the rotational motionthereto.
 19. The system of claim 16, further comprising a fluid-poweredturbine in fluid communication with a fluid chamber, reciprocation ofthe drive arm impelling fluid through the chamber to drive the turbine,and the turbine driving the electrical generator.
 20. A method forharnessing subsurface wave power, the method comprising: displaceablymounting a generally trapezoidal, biconcave wing underwater orientedgenerally perpendicularly to a sub-surface wave propagation direction;and reciprocating a drive arm using generally cyclic displacement of thewing.